[REVIEW 3-5] Fix regression in rendering Thai texts

[Kohei Yoshida]

Hi there,

I'd like to have

http://cgit.freedesktop.org/libreoffice/core/commit/?id=e57525b61af70a6ee33c26f979e724740cca8655

cherry-picked to the 3-5 branch to fix

https://bugs.freedesktop.org/show_bug.cgi?id=48431

It's also important that Bug 32530

https://bugs.freedesktop.org/show_bug.cgi?id=32530

remain fixed after this change, which I've checked to be the case.

Review and sign-off appreciated.

Kohei